Bush LED40127FHDCNTD No Picture

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  • Bloopeta
    Badcaps Veteran
    • Jun 2018
    • 526
    • United Kingdom

    #1

    Bush LED40127FHDCNTD No Picture

    Hi, I have a Bush LED40127FHDCNTD

    The TV powers on, and backlights illuminate solid, for a few seconds, but no image is diplayed, and after a few seconds the backlights become dimmer, and flicker exceptionally fast, like a strove light effect. No image is ever displayed on the screen.

    If I unplug the ribbon cable from mainboard to tcon/driver board, the backlights still act in the same strobe like manor, they do not stabilise

    Any advice greatly appreciated
    Attached Files
  • nomoresonys
    Badcaps Legend
    • Jan 2013
    • 12088
    • U.S.

    #2
    Re: Bush LED40127FHDCNTD No Picture

    Seems like the usual backlight circuit issue, either bad connection or bad led/s.

    Comment

    • Bloopeta
      Badcaps Veteran
      • Jun 2018
      • 526
      • United Kingdom

      #3
      Re: Bush LED40127FHDCNTD No Picture

      Originally posted by nomoresonys
      Seems like the usual backlight circuit issue, either bad connection or bad led/s.
      Would that affect the no image problem also??

      Comment

      • nomoresonys
        Badcaps Legend
        • Jan 2013
        • 12088
        • U.S.

        #4
        Re: Bush LED40127FHDCNTD No Picture

        Good question, maybe unplug the backlights at powerboard, look at the screen with a flashlight hit menu etc. see if you see any text or anything on screen.

        Comment

        • Bloopeta
          Badcaps Veteran
          • Jun 2018
          • 526
          • United Kingdom

          #5
          Re: Bush LED40127FHDCNTD No Picture

          Originally posted by nomoresonys
          Good question, maybe unplug the backlights at powerboard, look at the screen with a flashlight hit menu etc. see if you see any text or anything on screen.
          Ill give it a go.

          Just Ive been reading through some old threads where people have described the flashing backlight issue, but they still had an image, and could navigate through menus etc, where as I get nothing.

          Would there be any point illuminating the backlights with LED tester to see if they still flash? Or would that be pointless?

          Comment

          • nomoresonys
            Badcaps Legend
            • Jan 2013
            • 12088
            • U.S.

            #6
            Re: Bush LED40127FHDCNTD No Picture

            The tester might tell you if you are getting the proper voltage from the leds.

            Comment

            • Bloopeta
              Badcaps Veteran
              • Jun 2018
              • 526
              • United Kingdom

              #7
              Re: Bush LED40127FHDCNTD No Picture

              Originally posted by nomoresonys
              The tester might tell you if you are getting the proper voltage from the leds.
              How would I go about testing using this plug with being 6 wires?
              Attached Files

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Bush LED40127FHDCNTD No Picture

                Beside the flickering backlights, it should not affect the T-CON function to produce the image on the screen. Did you check to see if you do have 12VDC at both ends of the T-CON fuse with ref. to the chassis gnd?
                Never stop learning
                Basic LCD TV and Monitor troubleshooting guides.
                http://www.badcaps.net/forum/showthr...956#post305956

                Voltage Regulator (LDO) testing:
                http://www.badcaps.net/forum/showthr...999#post300999

                Inverter testing using old CFL:
                http://www.badcaps.net/forum/showthr...er+testing+cfl

                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                http://s807.photobucket.com/user/budm/library/

                TV Factory reset codes listing:
                http://www.badcaps.net/forum/showthread.php?t=24809

                Comment

                • Bloopeta
                  Badcaps Veteran
                  • Jun 2018
                  • 526
                  • United Kingdom

                  #9
                  Re: Bush LED40127FHDCNTD No Picture

                  Originally posted by budm
                  Beside the flickering backlights, it should not affect the T-CON function to produce the image on the screen. Did you check to see if you do have 12VDC at both ends of the T-CON fuse with ref. to the chassis gnd?
                  Yes m8 I did, steady 12.36v both sides

                  Dont know if its relevant, but there is what I would describe as a fluttering noise coming from the blue one on powerboard, I would say in sync with the flashing backlights
                  Attached Files

                  Comment

                  • Bloopeta
                    Badcaps Veteran
                    • Jun 2018
                    • 526
                    • United Kingdom

                    #10
                    Re: Bush LED40127FHDCNTD No Picture

                    Again, not sure if this is relevant but when TV firsts starts up, the screen illuminates brighter as you would expect and lights are steady, but no image, then after a few secomds dims down, and you get the pulsating/strobing backlights, which, the strobing tbh isnt so visable looking at the screen, its more noticable as I have the back cover removed and can be seen through the holes in the chassis from the rear.

                    I have tried to capture it in a dark room in the following attached pictures. Please note the 1st pic, when the screen is bright and steady, its not multicoloured, its just the usual grey you would expect as normal, but for some reason my camera shows colours lol
                    Attached Files

                    Comment

                    • Bloopeta
                      Badcaps Veteran
                      • Jun 2018
                      • 526
                      • United Kingdom

                      #11
                      Re: Bush LED40127FHDCNTD No Picture

                      I have stripped this down today, this is the first time I have came across a TV with backlight set up like this.

                      So all the backlights are lit, just with a strobe light effect. Have checked all the plugs and connections, no change.

                      What is the best way to go about testing these in the correct manor?
                      Attached Files

                      Comment

                      • Bloopeta
                        Badcaps Veteran
                        • Jun 2018
                        • 526
                        • United Kingdom

                        #12
                        Re: Bush LED40127FHDCNTD No Picture

                        Also, just having a look on the underside of the powerboard, and came across this bit, does that look strange to anyone? Or would that be normal???
                        Attached Files

                        Comment

                        • Bloopeta
                          Badcaps Veteran
                          • Jun 2018
                          • 526
                          • United Kingdom

                          #13
                          Re: Bush LED40127FHDCNTD No Picture

                          Do these readings look ok?? Readings taken with TV turned on and backlights strobing

                          Backlight Plug

                          1. 86.1v fluctuates up to 88.2v and down to 80.7v
                          2. 17.1v
                          3. 16.7v
                          4. 80.7v fluctuates 80.9v
                          5. 23.8v fluctuates 24.0v
                          6. 16.7v fluctuates 16.8v


                          Plug to Mainboard

                          1. 24.9v
                          2. 0v
                          3. 0v
                          4. 0v
                          5. 03.01v
                          6. 0v
                          7. 00.6v
                          8. 0v
                          9. 05.5v
                          10. 12.4v
                          11. 05.5v
                          12. 05.3v
                          13. 12.8v
                          14. 12.4v
                          15. 25.1v
                          16. 03.3v
                          17. 03.4v
                          18. 03.3v
                          19. 0v
                          20. 0v
                          Attached Files

                          Comment

                          • Bloopeta
                            Badcaps Veteran
                            • Jun 2018
                            • 526
                            • United Kingdom

                            #14
                            Re: Bush LED40127FHDCNTD No Picture

                            Anyone??

                            Comment

                            • Bloopeta
                              Badcaps Veteran
                              • Jun 2018
                              • 526
                              • United Kingdom

                              #15
                              Re: Bush LED40127FHDCNTD No Picture

                              Also, when inspecting the tcon/driver board, this capacitor cd7 looks a bit dodgy
                              Attached Files

                              Comment

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